Vacuum tube



May 15, 1934. w. VAN B. ROBERTS VACUUM TUBE Filed Sept. 27 1927 INVENTOR. WALTER VAN B.ROBERT5 BY g A TO RNEY

Patented May l5, 1934 UNITED STATl-ZS vacuum was Walter van B. Roberts, Princeton, N. 1., assigns! to Radio Corporation of America, a corporation of Delaware Aiipucaaon September 27, 1921, Serial No. 222,230

9 Claims. (01; zso-zu) This invention relates to .a vacuum tube and has for its object the provision of a thermionic vessel especially adapted for extremely short wave work.

In short wave work much trouble has been encountered due to stay capacity effects, for example due to the capacity between the leads of the oscillator circuits and the radiating elements. By my invention I reduce considerably these undesirable capacity effects by placing my radiating element in close contiguity with the Oscillating circuits and more particularly in one embodiment of my invention I place the radiating element or radiation receiving element, within a vacuum tube, coupled to a plate and a grid circuit. In other embodiments of my invention I accomplish the reduction of these undesired capacities by placing the antenna of the system on the outside of the tube containing oscillation circuits as well as the usual tube elements, or in still otherforms of my invention I combine the electrodes of the tube with the antenna structure.

Other objects of my invention and the manner of effecting them will be self-evident from a fuller description of my invention which shall appear hereinafter and which shall be given with the aid of the accompanying drawing in which:

Fig. 1 shows partially diagrammatically according to my invention, an improved thermionic vessel and receiving and transmitting circuits therefor;

Fig. 2 is a perspective view of an element utilized in a coupling varying arrangement for the antenna of the tube shown in Fig. 1;

Fig. 3 shows the combination of my tube shown in Fig. 1 and a parabolic reflector therefor;

Fig. 4 diagrammatically shows a part of a tube according to my invention having an antenna attached to the exterior of its envelope;

Fig. 5 shows diagrammatically another form of my invention wherein a radiating element is attached directly to the plate of my tube; and

Fig. 6 shows a part of another tube built according to my invention wherein the antenna is in two sections and attached directly to the grid battery 11 a source of plate potential is provided. An adjustable tap 12 is provided for varying the plate potential. Switch 13 connects in series with the plate circuit telephone 14 for receiving, and alternately a bumer 15 for transmitting 6 chopped waves. It is obvious, of course, that the buzzer 15 may bereplaced by a microphone for telephony if so desired. when transmitting, either the plate voltage or grid bias is varied until the tube is in an oscillating condition the frequency of oscillations being determined by the electrical constants of the antenna 16 which has a distributed capacity indicated by the dotted lines 17.

Due to thehigh frequencies involved the coupling between the plate circuit, grid circuit, and antenna may be simply the straight portion 18 of the lead to the grid, the straight portion 19 of the plate lead and the adjacent straight portion of the antenna 16. For lower frequencies a few turns may be introduced into either the antenna, straight portion 18 or straight portion 19 or any number of these parts as desired.

To. vary the capacity of the antenna circuit there is provided a metallic cylinder 20 which 30 may be adjusted along the portion of thetube 1 indicated by 21 by means of set screw 22. To vary the coupling between antenna and plate and grid circuits I provide at the other end 23 of my tube an adjusting device comprising a pair 5 of semi-cylindrical members 24 having arms 25 thereon which may be fastened abbut portion 23 of my tube by means of suitable bolts 26. A glass rod 27 is fused into the reentrant end 28 of my tube to which is also fused antenna 16. By means of set screws 29 and by virtue of the flexibility of the reentrant end 28 the curvature of the antenna 16 may be varied so that'the coupling between it and the grid and anode circuits may be varied.

If so desired, the antenna may be timed by leaving the antenna 16 protrude from each of the reentrant ends 28 of my tube and by cutting its length until it has the desired electrical characteristics.

To those skilled in the art it will be apparent that I have used in connection withmy tube a well known oscillation circuit, the radio frequency path between the plate lead and filament being through the natural capacity of the leads to the 105 plate and filament. However, it is clear that many other circuits may be used in connection with my tube and therefore I wish it to be understoodthatIamnottobelimitedbythe circuitindicated in P18. 1. 11g

In evacuating the tube it will be found desirable to degas the antenna 16. This may readily be. done by causing strong currents of the resonant frequency to flow in the antenna thereby heating it and causing the evolution of the occluded gases.

These currents may be induced in the antenna by suitable electrical apparatus.

In connection with the construction of antenna 16 shown in Fig. 1, it is to be noted that it is fused into the reentrant portions 28 of the elongated portions 21, 23 of tube 1. Portions 21, 23 extend preferably in a direction at right angles to the stem portion 1a of the tube so that antenna 16 itself lies along a line at right angles to the axis of stem portion la.

To cause antenna 16 to sag for varying the coupling, upper set screw 29 is unscrewed and the lower screw 29 is tightened forcing the right hand end of glass-rod 27 up. Due, to the flexibility of the reentrant portion 28 the fused end of rod 27 will be lowered, which in turn will cause antenna 16 tobend. A reverse process will, of course, cause antenna 16 to bend in the reverse direction.

In Fig. 3 I have shown the combination of the thermionic vessel shown in Fig. 1 and a parabolic reflector 30. The tube should be placed within the reflector so that the antenna lies along the line through the focus and at right angles to the plane of the parabola utilized in generating the warped surface of the reflector. This modification will be found extremely useful in times of war for use in trenches where directional transmission and reception are desirable.

In Fig. 4 I have shown a modification of my invention wherein the oscillator circuits are within the evacuated portion of my thermionic tube and wherein the antenna 40 is attached to the outside of the glass envelope by means of glass studs 41 which are fused about the antenna. The adjacency of the antenna and oscillator circuits allows the necessary transfer of energy.

Fig. 5 is another form of my invention wherein antenna and one of the electrodes are combined in the same elements, the electrode utilized in this case being the plate. Antenna 50, as shown, projects through the glass envelope of the tube. I

A tube wherein the antenna is made of the same metallic parts as compose the grid and plate is shown in Fig. 6. Elements 61 and 62 are attached to the grid and plate respectively of the tube, and project through the glass structure of the same.

While I have shown several preferred forms of my invention I do not intend to be limited thereby, but only by the breadth of the appended claims.

Having thus described my invention, what I claim is:

1. A thermionic device comprising an antenna,

a grid, a filament and a plate all within an evacuated envelope, means for tuning the antenna and means for varying the coupling between the antenna and a circuit within the en'- velope.

2. Portable apparatus comprising a thermionic tube having an antenna within its evacuated portion, and a reflector supported by said tube and movable therewith.

3. A thermionic tube housing an antenna, a grid, a filament and a plate all within the envelope of the tube and means carried by the tube for tuning the antenna.

4. A thermionic vacuum tube having an enclosing envelope, an input oscillatory circuit mounted within said envelope, an output oscillatory circuit mounted within said envelope, both said circuits being coupled together, and a substantially linear radiating element mounted within said envelope, a portion of said radiating element lying adjacent to and coupled to said input circuit, and another portion of said radiating element lying adjacent to and coupled to said output circuit. v

5. An electron discharge device having an evacuated container wherein are contained an anode, an electron emitting cathode, and a control grid, an antenna carried by said container, and, a reflector penetrated by said device.

6. An electron discharge device having an anode, a cathode, and a control grid mounted within an evacuated container, a straight wire antenna carried by the container, and, a curved metallic reflector penetrated by said device, said antenna lying substantially along the focal axis of the reflector.

7. An electron discharge device comprising an evacuated container wherein a'recontained an electron emitting cathode, an anode and a grid, and, a metallic reflector penetrated by said device for increasing the directional efiect of high frequency oscillations to be received or propagated by said device.

8. An electron discharge device comprising a.

cathode, anode and control electrode within an evacuated container, individual leads for said anode and control electrodes, astraight linear antenna, each of said leads having straight linear portions within said container extending parallel to said antenna and individually coupling said grid and anode electrodes to said antenna.

9. An electron discharge device comprising a cathode, anode and control electrode within an evacuated container, individual leads for said anode and control electrodes, each of said leads having straight linear portions within said container, other straight linear elements forming radiators coupled to each of said first linear portions.

WALTER VAN B. ROBERTS. 

